CZ392192A3 - Spliced material, process for preparing thereof, and apparatus for making the same - Google Patents

Abstract

PCT No. PCT/SE91/00779 Sec. 371 Date May 11, 1993 Sec. 102(e) Date May 11, 1993 PCT Filed Nov. 18, 1991 PCT Pub. No. WO92/08832 PCT Pub. Date May 29, 1992.The present invention relates to a method for producing spunlace material in which there is formed a fibrous web by air-laying a layer of fibres of staple length on a forming wire and air-laying a layer of short fibres on top of the layer of staple fibres. According to the invention, the fibrous web is passed to an entangling wire 18 on which there is arranged at least one elongated element 17 whose diameter is much greater than the diameter of the wires 16 in the entangling wire 18, whereafter the fibrous web is entangled. The invention also relates to an arrangement for carrying out the method, and to a spunlace material produced in accordance with the method.

Description

The present invention relates to a method and an arrangement and apparatuses for the production of a spun lattice fabric material, a method for its production and an arrangement of apparatuses for its production. In particular, but not exclusively, the invention relates to a spun lattice fabric suitable for use in absorbent packaging layers of useful goods such as diapers, sanitary napkins and the like.

BACKGROUND OF THE INVENTION

The spun grid comprises a mechanically nonwoven fabric in which the blocking of the fibers and the fibrous structure is achieved by splicing the fibers of the fibrous fabric using thin air or liquid jets, i.e. the structure is obtained by means of a so-called splicing process. which is produced by wetting, for example, entanglement is achieved by means of liquid jets. Such a material has distinctly textile-like properties as compared to other nonwoven fabrics and also provides a relatively high degree of flexibility in the manufacturing method and properties of the material being made, due to the fact that the properties of the material can be varied to a great extent by perfectly appropriate selection As a result, the use of spun grid is becoming more and more common.

Such a material can be effectively used to dry or absorb liquid as well as to disperse or disperse liquid by coming into contact with it. Another area in which the spun grid can be used is in the absorbent layers of the absorbent article where the material is felt to have a textile-like structure, but is more comfortable to the user's skin than other types of nonwoven materials that are often felt, as they would have a plastic texture.

SUMMARY OF THE INVENTION

The present invention relates to a method and an arrangement for producing a spun grid fabric, which may advantageously be used as a liquid dispersion layer or as a covering layer of an absorbent body in a utility article, and also relates to a spun grid fabric produced according to the invention with properties which allow the liquid to disperse or disperse.

The inventive method comprises an air-guided fiber layer having a length of staple fibers per forming wire and an air-guided short fiber layer on top of the staple fiber layer to form a fibrous web. The method is characterized by transferring the fibrous web to the entangling wire net, on which at least one elongated element is placed, the diameter of which is significantly greater than the diameter of the net wires from which the entanglement wire is formed, and the entangling of the fibrous web on that wire. Once the fabric is entangled, the elongated string, which contains only staple fibers, is formed with each portion of the spun grid fabric that is placed over the stretched element that is placed on the entanglement net during the entanglement process. By placing a plurality of such stretched elements on the mesh, the obtained material will have a banded structure in which short fibers are collected in the gaps between the stretched elements and because only staple fibers remain on the tops of the stretched elements. If the process involves the use of hydrophobic staple fibers and hydrophilic short fibers, for example cellulosic fibers, and if a braided wire mesh is used, the mesh size of which is such that the spun grid fabric produced is perforated by holes. The material obtained will disperse or disperse the liquid in its longitudinal direction. Such a material is particularly suitable for use as a liquid dispersing layer in an absorbent body of a utility such as a diaper, a sanitary napkin or the like to increase the liquid dispersion in the longitudinal direction of the article. The longitudinal dispersion of the absorbent pads is such that the absorbent pads are fully supported by the absorbent pad,

According to one embodiment of the invention, the staple fibers are elastic. This provides a spun lattice fabric that is elastic only within those portions that contain only staple fibers, because stretching of the elastic fibers in the second portions is prevented by binding said fibers to the cellulosic fibers. Furthermore, it has been found that staple fibers are generally directed transversely to these strings in the bands between the elongated strings of the braid and the staple fibers of the entangled material. This allows the direction of stretching of the finished material to be controlled by changing the alignment of the stretched elements with respect to the direction of alignment.

The inventive arrangement for producing a spun lattice fabric comprises a forming unit having a staple fiber former and a short fiber former having the function of guiding air through the staple fiber layer to the forming wire and airborne the short fiber layer on the staple fiber layer to form a fibrous web. , and a twisting unit for hydroentangling the fibrous web. The arrangement is characterized in that the splicing unit comprises a splicing wire net having at least one stretched element whose diameter is much larger than the diameter of the wires from which the splicing wire net is constructed.

The spun lattice fabric produced according to the invention is characterized in that it is made of short fibers and fibers with a length of staple fibers and that it comprises at least one elongated cord material which comprises only staple fibers.

BRIEF DESCRIPTION OF THE DRAWINGS

For clarity of the invention, its main features with respect to the exemplary embodiment and its main features with respect to the exemplary embodiment and Laké with reference to the accompanying drawings, in which FIG. 1 shows schematically the arrangement of apparatuses for producing a spun grid FIG. 2 shows a partial side view of the forming line contained in the arrangement shown in FIG. 1; FIG. 3 shows a perspective view of a flying wire net according to the prior art. d an axial cross-section of a portion of the braiding wire shown in onr, 3, v? on a larger scale

EXAMPLE 1 Performing a judgment

The spun lattice fabric produced according to the described embodiment of the invention consists of dry cellulosic fibers and hydrophobic staple fibers, wherein said staple fibers consist of polyester fibers having a scapiose fiber length of 20-50 mm.

FIG. 1 shows an arrangement for producing a spun grid fabric comprising a forming station 1 and a splicing station 2. The arrangement may also include a staple fiber processing station 3, for example pre-carding, and a post-treatment station 4 for the produced spun grid fabric and rolling station. 5 in which the spun grid fabric is rolled into rolls.

The forming station 1 comprises a staple fiber former ΰ and a short fiber former 7, which may be of the known type, and the function of which is to guide the respective staple fiber layer and the clear fibers by air to the lower forming wire. The opener station 2 comprises a plurality of rows of lines having a diameter of 70-130 microns, from which water is sprayed under pressure into the lower twisting wires.

Giant. 2 shows a preferred embodiment of the inventive station.

The filaments and filaments of the filaments 6 are highlighted.

it contains three cylinders! The open and discrete staple fibers are staggered from the edges of the carding roller 10 by a perfectly coupled centrifugal force generated by rotation of the carding roller and the air flow symbolically represented by the arrow A in FIG. 2. This air flow is directed tangentially through the cylinder? in a position where the staple fibers are dropped from the roll. The staple fiber former also comprises two coaxial rollers, a scraper 11 and a work roller 12.

The staple fiber former 6 shown in FIG.

The carpet of transversely opened staple fibers is guided by a toothed roller 9 into a nip defined between the edges of the roller 9 and the back pressure device 13 of the so-called compression bar. A carding roller 10, which is provided with teeth or the like, with gripping jaws at the front through which the advanced staple fiber carpet enters. The lowermost fibers in the transverse open fibrous carpet are so efficiently combed through the carding roller teeth. Once the carpet is transferred from the feed roller to the carding roller, it is accelerated to pass around the pointed edge of the push bar 13 to facilitate opening and independence of the staple itself. - fibers. The uppermost fibers in the transported fibrous carpet are not opened and separated as well as the lowermost fibers and will be clamped by the work roll 12 which rotates with the rakes at a slower speed than the carding roller 10. The fibers picked up by the work roll are transported to the fold 11 using the rake on the carding roller. The work roller and the scraper are also provided with teeth or a similar combing device, and the fibers which have been most difficult to open and separate and which are retained by the work roller will thus be further opened and self-contained by the perfect action of the teeth on these rollers. The fibers which pass between the working and carding roll, which are then thrown from the edge of the raying roll and generated by centrifugal force, are therefore fully opened and separated. The function of the air stream A is to carry staple fibers which are thrown from the edge of the card roller to the lower forming wire 3.

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From the above method of operation of the staple fiber former, it is clear that t and r generally works as conventional and commercial staple fiber former, such as Fehler K 21, etc., which can be successfully used in the inventive arrangement,

The forming station also includes a pulp forming machine of the type capable of throwing the pulp fibers P perfectly onto a steel mesh or the like.

As shown in FIG. 2, the staple fibers S are fed first onto the forming wire 8, while the cellulosic fibers are fed to the top of the staple fiber layer. The air-guided fibers are returned to the wire 8 by means of the vacuum generated in the suction box 15, only its end walls are shown in FIG.

The fibrous fabric formed in the forming station 1 is then conveyed to the splicing station 2 and there undergoes a first splicing process under low medium pressure. In this first splicing process, the staple and cellulosic fibers are bound to each other to allow the formation of a fibrous web that resists the subsequent splicing process under high pressure without flushing the cellulosic fibers away or disintegrating.

Figures 3 and 4 schematically illustrate a preferred embodiment of a twisting wire netting 18, which can advantageously be used in a second twisting process which operates under high pressure. The twisting device comprises a cylindrical net 16 which is mounted in the twisting station for rotation in the same manner (not shown) below the nozzles through which the water flows. The wire 17 is wound spirally around the cylindrical surface of the mesh 16 and engaged at least at the ends on the wire mesh.

As can be seen in Figures 3 and 4, the diameter of the wire 17 is much larger than the diameter of the wires forming the net 16. The difference between the turns of the spiral wound is shown in Figure 3. This difference is suitable in the range of 1 to 10 times the diameter wire 17.

Subsequently, the pulp is subjected to a first stranding process at a low medium pressure (60-100 bar). The fibrous web is then conveyed to the stranding apparatus 18 and is stranded there at a high pressure (80-250 bar). The jets of water from the water jets that impinge on the elongated elements 17-17, which are formed by a spiral wound wire 17, pass to the underside of the elongated elements and carry portions of cellular fibers initially located on the upper side of the elongated elements 17 ^ - 17 _{n> The} cellulosic fibers will therefore collect in the gaps between the mutually delimited stretched elements 17-17, e.g. between the elements 17 ... 17 and 17-17, as shown ⁷ schematically in Fig. 4. Due to the greater length of the staple fibers as compared to cellulose fibers, the separate staple fibers will bind to each other and to the cellulosic fibers at several positions according to their length and will thus be quite much more difficult to move than the cellulosic fibers. As a result, the staple fibers will not go down into the gaps between adjacent stretched elements, but will return to the tops or upper surfaces of said elements. It is true that several free ends of staple fibers may pass down into the gaps between the stretched elements, but since the staple fibers as a whole cannot move with the water flow to the underside of the stretched elements, the free ends of the staple fibers will move and subsequently most of these free ends of the staple fibers will be captured by the other staple fibers and bound together with each other before leaving the tops of the stretched elements.

The entanglement takes place typically in the gaps between adjacent stretched elements, i.e. the permeability of the wire mesh 16 to the liquid is sufficient for the water in the beams to flow perfectly unhindered through the mesh and subsequently transfer a large part of the kinetic energy obtained to the fibers of the fibrous fabric. It is pointed out that the result of the circular shape is that the spiral wound wire will increase the open area of the wire mesh and hence the permeability of the capaldna only to a small extent,

The staple fibers may be guided in a layer of such a thickness that the subsequent second twisting process of the fibrous fabric will create holes in strings of only staple fibers formed along the upper sides of the stretched elements.

The subsequently produced mesh fabric, which has passed through the splicing station 2, passes through a further processing station 4 where the material is dried and optionally subjected to a further treatment such as dyeing or surface treatment. The spun grid is then rolled onto the rollers in the rolling station 5.

For example, a preferred spun lattice fabric summarized in this manner will comprise only staple fibers on the surface between the strings of mixed cellulosic and staple fibers. Such a material may advantageously be used as a liquid-permeable backing layer through the absorbent pad, since the cellulose and staple fiber strings are capable of dispersing or dispersing the liquid in its longitudinal directions. This makes it possible to position the main part of the absorbent pad for liquid absorption, thereby reducing the risk of the absorbent pad being locally saturated, and also reducing the leakage associated with saturation. The use of the inventive spun lattice fabric as a liquid scattering layer of the utility article allows the full absorbent capacity to absorb the liquid and utilize the absorbent pads more efficiently.

As can be seen, the above-described spun grid material can also be used for drying or as a liquid dispersion layer in other regions where dispersion or dispersion of liquid in a given direction is desirable.

The above-described method and arrangement according to the invention also allows a material of controlled elasticity to be produced, e.g. a material that can be stretched in a specific direction. Such a material is obtained when the fibers comprise elastic fibers. It has been found that in those portions of the material that contain only staple fibers, these fibers will generally be oriented transversely to the elongate elements, as a result of which the elongated elongated staple fibers will be flushed down into the gaps between stretched elements in the same manner as pulp fibers or water jet.

In braided and staple fiber strands, the material will generally be non-elastic regardless of whether the staple fibers are elastic or not because the staple fibers are bound to the inelastic pulp fibers. It can be observed that by using the elastic staple fibers according to the inventive method, a material is obtained which is capable of stretching in its transverse direction relative to the stretched elements. Since the alignment of the elongated elements with respect to the directional arrangement can be varied by ± 45 *, it is possible to control the elongation direction largely by appropriately positioning the elongated elements.

According to one variation of this embodiment of the invention, the elastic fibers may comprise bicomponent fibers which shrink under heat and which become elastic upon shrinkage. Such elastic fibers may be used to produce a material according to the invention in which the difference between the pulp strings and the staple fibers is very small even zero.

It can be seen that the above methods can be used within the scope of the invention, eg instead of a spiral wound wire that produces elongated strings that extend slightly inclined to the direction of alignment, one or more stretched elements may be attached to the bottom wire in a suitable manner, the wire is then preferably straight, with no inclination as to the direction of the arrangement. Further, the stretched elements may be. transversally shaped other than circular, although this shape is particularly suitable in terms of liquid flow and permeability. The stretched elements may also be given in a wavy configuration, e.g., a sinusoidal configuration, or may be set discontinuously or continuously diagonally. The extent to which short fibers are flushed or rinsed from the tops of the stretched elements can be varied in terms of different material being produced and in terms of the same material by varying the diameter of the stretched elements. Further, the stretched elements need not be stretched over the entire wire mesh, giving the possibility of forming a striped spun fabric that it is made with different stripes. Neither need be. the stretched elements are inclined at the same angle to the direction of arrangement

It can be observed that the inventive method can be used in the manufacture of other types of spun lattice fabric material than the material described in accordance with an embodiment of the invention. For example, the inventive method can be used to produce only liquid-impermeable staple fibers and portions of mixed short and liquid impervious staple fibers based on hydrophilic short fibers and hydrophobic staple fibers by appropriately selecting the mesh size of the wire mesh. The invention is therefore limited only by the following points.

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PATENTOVÉ

MODIFIED

Claims ^

Claims (2)

Claims ^ - I cp le t e n o - - I · W o rs of production -ρ class; in which the fibrous fabric is formed by over-guiding the staple fiber layer to the shaping wire and by conducting short fibers by air at the top of the layer. staple fibers, characterized in that by conveying the fibrous web to a strand of wire, on which at least one stretched element is placed, the diameter of which is significantly larger than the diameter of the strand from which the strand of wire is constructed and the subsequent stranding fibrous fabric The arrangement for producing a spun lattice fabric comprises a forming unit (1) comprising a staple fiber former (6) and a short fiber former (7) operating to guide the staple fiber layer to the forming wire (8) and guide the short fiber layer at the top of said layer. and further comprising a splicing unit (2) for braiding the fibrous fabric at high pressure, MORE THAT the splicing unit (2) comprises a splicing device (18) on which at least one stretched element (17) is located, the diameter of which is significantly larger than the diameter of the wire (16) from which the splicing wire device (18) is constructed. Arrangement according to Claim 2, characterized in that each of the elongated elements (1?) Comprises a plurality of longitudinally extending, mutually parallel wires 17 - - 17 _{η of a} circular cross-section arranged on the twisting wire device (18). 4. Arrangement according to claim 3, characterized in that the longitudinally extending elements are inclined with respect to the direction of the arrangement. 5. Arrangement according to claim 4, characterized in that the stranding wire device (13) has the shape of a hollow cylinder (16) and that the longitudinally extending, parallel elements comprise a single wire (17) which is wound spiral around the edge of the spun wire. L · s p o ř á dání according to b o d u 2, o bs and h u .ící amount on t a women c li p r V k ú , ’Y z n a é u j 1 c and s e that pr v k y j s o u tilt y n r ú z n v c h ú h i ech ke s m ě r u arrangement • Prede n ý m ř Even from the o ý weaving new mate r i á 1 , v y z n and i'3 u J í c characterized in that it is composed of short fibers (P) and fibers with a length of staple fibers (S), and comprises at least one longitudinally drawn string of material composed solely of staple fibers 8. The spunbond web of claim 7, wherein the short fibers (P) are hydrophilic while the staple fibers (S) are hydrophobic. 9. A spunbond web according to claim 8, characterized in that the short fibers (P) are cellulosic fibers 10. The spun grid material of one of the items characterized in that it is liquid impermeable 11. The spun grid material of one of the items 7-10, characterized by the fibers (S) being elastic fibers in that staple Use of a stretched member attached to a twisting wire device such that a longitudinally extending string of material containing only staple fibers in a spun material consisting of short fibers and staple fiber lengths is produced. FIG.lv ¹ · 'jv' • · ^, · ι :: ·. ^,, ··, · 1ι ₁ ^ί ·: ^ι · ν; ' * ,, J 'i if 1 r ^r l' f IXR, 'U ,, -u' ¹ * i. IH. ¹ '· ^υ ' ui FIG.2 n _r ,. m 2/2 FIGÁ